The invention relates to a reamer for the fine machining of surfaces of drilled holes in metal workpieces, and particularly to the orientation of a chip deflector of the reamer.
Reamers of the type discussed herein are used for fine machining of surfaces of previously drilled holes, both through holes and blind holes in metal workpieces. The reamers comprise at least one main blade and at least one auxiliary blade. Frequently, such known reamers are provided with at least one cutter plate, which supports the main and auxiliary blades.
An important aspect of the fine machining of surfaces of drilled holes is controlling movement of the chips formed. The chips have to not only be broken but also transported away from the drilled hole being machined in such a manner that they cannot come between the tool and the surface of the drilled hole. In machining through holes and blind holes, different reamers are used to control the chip progression accordingly. The reamers are equipped with differently oriented main and auxiliary blades. These are disposed so that they do not run parallel to a plane intersecting the central axis or the axis of rotation of the tool but instead they enclose an acute angle with the axis. This configuration ensures a right-hand or a left-hand twist of the chips. In reamers that are provided with cutter plates, the cutter plates are disposed within the tool body so that they do not lie parallel to a plane intersecting the central axis or the axis of rotation of the tool but they instead enclose an acute angle with the axis, in order to ensure a right-hand or left-hand twist of the chips. It is apparent that the production of various tools for machining through holes and blind holes is elaborate and therefore cost-intensive.
It is an object of the invention to provide a reamer that does not exhibit the above described disadvantage.
To achieve this object, a reamer for fine machining of surfaces of drilled holes in metal workpieces is proposed which has a main blade extending back from the front end surface of the reamer body and rising in height followed by an auxiliary blade which meets the main blade at an apex or corner. The auxiliary blade descends at a very slight angle rearwardly from the apex with the main blade.
A chip transport surface adjoins the blades at the side to which the chips are urged by the blades.
A chip deflector step is provided at the edge of the chip transport surface. The chip deflector rises in the zone of the main blade in the direction toward the front of the reamer body, which means the step descends or falls off rearwardly. This means that the chip deflector step exhibits a decreasing distance from the main blade. The chip deflector step is so disposed that it also extends in the zone of the main blade at a decreasing distance from a theoretical continuation of an outer edge of the reamer again in the direction toward the front. This tool is simple and economical to produce.
The chip deflector step also extends rearwardly past the auxiliary blade and descends or drops off in the rearward direction, increasing the distance away from the auxiliary blade. A particularly preferred embodiment of the reamer includes at least one cutter plate, which encompasses the main and auxiliary blades. This cutter plate includes the chip deflector step which, as described above, rises forwardly in the zone of the main blade of the cutter plate, thereby exhibiting a decreasing distance in the forward direction from the main blade and from a theoretical continuation of the outer edge of the cutter plate.
In a preferred embodiment of the reamer, the chip deflector step is of linear extent or shape. As the chip deflector step is generally produced in a grinding operation, such a configuration is particularly economical to produce.
In a further preferred embodiment of the reamer, the cutter plate is disposed parallel to the central axis or axis of rotation of the reamer. It is therefore possible to equip existing reamers with a cutter plate of the type discussed here and to machine blind holes without a problem, since the chips formed in reaming can be easily removed. This even applies in conjunction with what is known as minimal volume flushing, in which relatively little flushing medium and coolant is used during the machining of the workpiece surface.
Other objects and features of the invention are described below with reference to the drawings.